Manufacturing paper-pulp.



Patented June '7, 1904.

PATENT OFFICE.

OMA CARR, OF BUENAVISTA, VIRGINIA.

' MANUFACTURING PAPER-PULP.

SPECIFICATION forming part of Letters Patent No. 762,139, dated June '7, 1904. Application filed AprilZZ, 1903. Serial No. 153,764. (No specimens) To all whom it may concern.-

Be it known that I, OMA CARR, a citizen of the United States of America, and a resident of Buenavista, county of Rockbridge, State of Virginia, have invented a new and useful Method of Manufacturing Paper-Pulp, of which the following is a full, clear, and exact specification.

The object of my invention is to provide a method whereby paper-pulp may be manufactured from chestnut, chestnut-oak, and other similar tanniferous woods and at the same time extract and conserve the tannin extractives of such Woods for the purpose of tanning, as more fully hereinafter described.

The chestnut-Wood, taken as an example of the woods to which this invention is applicable, contains from five per cent. to twelve per cent. of tannin extractives on the Waterfree Wood. Such extractives are the base of the present industry of manufacturing tanning extract, at this time a staple material in use over the United States and Europe in the manufacture of leather. In such manufacture of tanning extract as now carried on the operation is conducted as follows: The tree, being felled, is split into convenient sizes and transported to the works. There it is chipped, the chips passed through regrinding-machines for the purpose of finely dividing the material across and with the fiber (the degree of such division having a vital effect on the economy of the succeeding process of extraction) and then subjected to leaching treatment in open tubs having false bottoms and suitable mechanism for heating, circulation of liquor, &c. The liquor so obtained is suitably clarified, concentrated by evaporation to the desired density, and packaged. The method in universal use for such extraction is that above givenopen tubs from twelve to sixteen feet in diameter, ten to sixteen feet in depth, with pumps, air or steam lifts, for circulating the liquor from beneath the false bottom of one tub and depositing it upon the surface of the tub next in the series. A temperature of 180 Fahrenheit is rarely exceeded, and the material is under treatment from three to five days.

If the chips have been brought to a state of fineness permitting efficient extraction by the process described, they present after such extraction these characteristics: (a) They are short in fiber, not over one-eighth inch; (7)) they carry large quantities of dust; (c) the coloring-matter has been markedly fixed upon the fiber; (d) from one and one-half to two and one-half per cent. of tannin extractives still remain. Such chips have no applicability to the purpose of preparing staple pulp or paper products and are therefore burned for fuel, yielding a return of but approximately forty cents on the original cord against a pulp value, under present conditions of market, of ten dollars.

To render such material applicable to the purpose of preparing pulp or paper products of high quality involves means for (a) retaining long fiber, (b) avoiding dust, (c) removal of tannin extractives and other acid or fixable colors. To accomplish the first and second of these requires that the material be primarily coarsely divided, and on material so divided the third of these requires a system of extraction capable of promoting the osmotic action far beyond the same phenomenon if applied to such chips by the conventional method of tannin extraction. The length of fiber and freedom from dust particles determines nearly entirely the strength of the sheetpulp, paper, card, or other product. The removal of color prior to digestion for pulp determines the extent to which the soda or sulfite may be affected by such colors (acid in nature) and has a heavy bearing upon the efliciency of the bleach.

Inasmuch as it is desirable that established extract plants may be converted at minimum expense into adjuncts of pulp or paper plants and inasmuch as it is desirable that new plants may employ the best methods obtainable I describe two processes of securing the condition of chip contemplated in this invention.

First. In established extract plants I employ chippers giving a chip of the desired length and regrind such chip in a conventional shredding-machine to break the chip parallel with its fiber. Such chips are conveyed to conventional lcaches and the usual method pursued therein until the chips are ready for discharge. Instead of going to the furnaces the chips are conveyed through heavy rolls or burs or other suitable. mechanism, the object being to crush the softened chip, causing its fibers to separate without breaking or losing in strength. At this point the chips contain from three to eight percent. of tannin extractives, and it is necessary, to remove such resid- 'ual extractives, that the chip be crushed or its fiber loosened. Having been thus treated, the fiber is conveyed to a second series of leaches, where it is releached systematically, clean hot water being its final bath. Drained and discharged, the chip is ready for the pulpdigester. In practice the liquors derived from the secondary leaching are passed to the primary leaches as water would be in the conventional methodand there brought to maxi-' mum concentration by contact with fresher and stronger chips. The point in this process is that by operating first upon a large chip it becomes softened in the primary soaking and may be suitably crushed to separate its fiber without impairing the same. On such crushed fiber the secondary leaching removes the residual extractives and leaves the chips open, free of dust, and in the best condition to receive the pulping solution. derstood that I do not confine myself to the double leaching set forth above for established extract plants, as the method may be varied considerably without departing from my invention.

Second. In new plants I apply the principle of operating upon a large chip as follows: Using the chipper yielding the desired chip, I subject such chips to the action of a suitable solvent (water, alcohols, acetone, &c.,) under such pressure higher than atmospheric, with corresponding temperature, as will expedite the osmotic action of the solvent in the desired measure. Using water, the pressure upon solvent and material should be near thirty-live pounds per square inch absolute, corresponding temperature 260 Fahrenheit. Using alcohols, the pressures and temperatures necessary will be found to be less than for water and the solvent subjected to recovery as in conventional processes, except where water is employed as the solvent, in which case it may be separated from the b y-products in any suitable manner and allowed. to go to waste. Any suitable container closed may be employed, so long as it shall be constructed of material not giving colored products with the tannin extractivescopper, brass, bronze, wood, &c. Means must be provided to care for the air expelled from the cellular spaces of the wood during saturation by the solvent-- suitably a vacuum-tank connected by piping with the container, communication to be established as the material saturates with sol- It will of course be unvent. Heat may be applied by direct injection of steam or through coils or tubes. The material should be subjected to treatment as described expeditiously to avoid molecular changes in the coloring-matters. If the containers be arranged serially, fresh solvent may be passing upon nearly-exhausted wood, the newer or richer material yielding liquors of high concentration to facilitate subsequent evaporation in the preparation of extract. The material should not be under such treatment much longer than five hours. WVhen the chips are finally exhausted to a trace of tannin, they are discharged, suitably drained or dried, and passed forward to the pulp-digesters. They are found clear of coloringmatters having undue effect upon the economy of bleaching after pulping, free of dust, and the cellular structure opening admirably for the entrance of the-pulping solution.

It will be observed that by both processes or any other process of extraction prior to pulping the invention consists in bringing the material to a state of fiber sufficiently long for paper-making and in a state of parallel division as affecting the sectional area across the grain which will permit efficient diffusion. Such condition of fiber or chip may be brought about by any suitable mechanism before cliffusion is begun, in which event the solvent process is rendered brief and devoid of possible damaging action on the fiber or undesirable fixation of color. Whatever processes of reducing the wood and extracting the tannins may be employed, it is essential that the chip or fiber shall be suffieiently long for paper and of sectional area across the grain per mitting efficient diffusion.

Thus by these plans is accomplished (a) the conservation of the tannin extractives in the form of a liquor ready for conventional clarification and evaporation; (7)) the residual chip has a length of fiber furnishing the finest quality of pulp and paper as to strength; the coloring-matters which would otherwise neutralize or unbalance the pulping solution and entail a prohibitory cost for bleach have been removed; (d) the fixation of color on the fiber has been avoided.

Having thus described my invention, what I claim, and desire to cover by Letters Patent, is

1. The process of extracting tannin and manufacturing paper-pulp from woods containing tannins, consisting in reducing the wood to chips having a length of fiber sufficient for paper-making, said chips being fine enough parallel with their fibers for efiicient diffusion, then extracting and conserving the tannins in their free, acid state without injuring the fiber, and then pulping the chips.

2. The method of manufacturing paper-pulp and tannins from wood containing tannins, consisting in reducing the wood to chips havmga fiber suificiently long for paper-making, said chips being fine enough parallel With their fiber for efiicient diffusion, then dissolving out the soluble tannins, and then pulping the chips.

' 3. The method of manufacturing paper-pulp and tannins, from Wood containing tannins, consisting in reducing the wood to pieces having a fiber sufliciently long for paper-making IO and fine enough in parallel division for eflicient diffusion, then dissolving out the solu-' ble tannins, conserving the extracted tannins, and then pulping the chips.

In testimony whereof I hereunto afiix my signature, in the presence of two Witnesses, 5

this 18th day of April, 1903.

v OMA CARR;

Witnesses:

H; T. WILSON, G.- H; BAILIE; 

